I have 18 categories = 2 x 8 drawer really useful storage towers.
1 drawer is a work in progress drawer though and the large models recently rebuilt are on shelves. Hang on, let me describe them - I know it drove me crazy as well - you have to have some shared categories and misc bits:
Unit 1
D1. ALL white bricks not currently in a model or part of a special category - including, very importantly - the solid colour little dot bricks of this colour
D2. As above, Dark grey bricks
D3. Blue (all shades)
D4. Light Grey
D5. Green (all shades) and pink (so high contrast)
D6. Yellow and Brown
D7. Black and Orange
D8. Red and Beige
Unit 2
D1. Small models and work in progress drawer
D2. Minifigures with associated parapanalia
D3. All the bits that don't fit elsewhere - mainly the see through dots, lights, etc - THIS IS THE CRUCIAL MISC DRAWER
D4. Anything to do with vehicles = wheels, bits the wheels go on, aerials, steering wheels, crane bits, little boats etc
D5. House Building - windows, doors, shutters, gates, flowers etc - also put the windowy bits from vehicles in hear - the perspex windscreen things - lost an hour or so debating whether theseshould o in drawer above
D6. Lego Bionicle bits
D7. Instructions
D8. Lego Magazines/book
Yes I am sad/need to get a life - but with 3 boys all mad on lego (including 1y old already!) I think it was time well invested. Good Luck my friend.